(353e) Characterization of Daunomycin Binding Affinity Toward Specifically Engineered DNA Sequences to Modulate Behavior of Nanoscale Drug Delivery Vehicles

Utilizing the properties of sequence specific nucleic acid biomaterials produces innovative and personalized drug delivery platforms. Nucleic acid aptamers have emerged as a versatile targeting agent for biomarker detection and imaging. Exploiting the binding mechanics between drugs and nucleic acids leads to groundbreaking nanoscale devices capable of targeting cells with high specificity and controlled drug payload release. We have synthesized, characterized, and optimized a novel nucleic acid biomaterial based nanocarrier capable of cell specific targeting, as well as modulating affinity and release rate of drug based on DNA sequence and structure.

Our work involves conjugating 15nm gold nanoparticles with aptamers attached to “anchor” DNA. “Anchor” DNA are short oligonucleotides that allow for a combination of different aptamers to bind to a single nanocarrier for potential to create personalized tumor treatment vehicles. Using a salt aging protocol and quantifying with radioactivity, we were able to design 15nm gold nanoparticles with a range of aptamers bound between 70 to 101 +/- 8 DNA strands. Additionally, four DNA sequence specific strands were engineered to have different binding affinities towards Daunomycin, a natural DNA intercalating molecule and chemotherapeutic drug.

Our studies showed binding of greater than 600 Daunomycin molecules to each nanoparticle, which is a several fold increase compared to other published literature pertaining to similarly sized nanoparticles. Drug loading can be increased further via larger nanoparticles and therefore greater surface area, or by increasing the length of the double stranded anchor and aptamer complex. We tested Daunomycin binding affinity to four different 52bp DNA sequences. Three of the strands are comprised of varying configurations of A-G-C repeats, a known favorable binding site for Daunomycin, while the fourth contains no G-C repeats. The DNA strands and their complementary sequences were hybridized, which was confirmed with gel analysis. These four duplexes, along with their single stranded components as controls, were incubated with increasing molar ratios of Daunomycin. Fluorescence measurements provided a ratio of bound drug per DNA construct.

Results indicate different binding affinities for each DNA sequence tested. This supports our theory that variance in DNA sequences on the nanoparticles can be used to modulate the release of Daunomycin. When observed in tandem with the nanoparticle, we are able to effectively quantify loading and release rates of Daunomycin from our aptamer linked nanocarrier. We have also shown that these nanoparticles are capable of delivering Daunomycin to small-cell lung cancer cells in vitro. Our novel, nucleic acid targeting and drug carrying device, is a transformative tool which will generate a wide number of related biomaterial platforms with the capability to modulate drug loading and release for effective and personalized cancer treatment.